La-ilaha-illa-Allah.

There is no god but the God.

While the faithful scurried to mosques, the rest of the city carried on without a glance; raucous university students drank beer, businessmen closed deals, merchants hawked spices and rugs, and tourists watched it all in wonder.

This was a world divided, a city of opposing forces—religious, secular; ancient, modern; Eastern, Western. Straddling the geographic boundary between Europe and Asia, this timeless city was quite literally the bridge from the Old World … to a world that was even older.

Istanbul.

While no longer the capital of Turkey, it had served over the centuries as the epicenter of three distinct empires—the Byzantine, the Roman, and the Ottoman. For this reason, Istanbul was arguably one of the most historically diverse locations on earth. From Topkapi Palace to the Blue Mosque to the Castle of the Seven Towers, the city is teeming with folkloric tales of battle, glory, and defeat.

Tonight, high in the night sky above its bustling masses, a C-130 transport plane was descending through a gathering storm front, on final approach to Atatürk Airport. Inside the cockpit, buckled into the jump seat behind the pilots, Robert Langdon peered out through the windshield, relieved that he had been offered a seat with a view.

He was feeling somewhat refreshed after having had something to eat and then dozing at the rear of the plane for nearly an hour of much-needed rest.

Now, off to his right, Langdon could see the lights of Istanbul, a glistening, horn-shaped peninsula jutting into the blackness of the Sea of Marmara. This was the European side, separated from its Asian sister by a sinuous ribbon of darkness.

The Bosporus waterway.

At a glance, the Bosporus appeared as a wide gash that severed Istanbul in two. In fact, Langdon knew the channel was the lifeblood of Istanbul’s commerce. In addition to providing the city with two coastlines rather than one, the Bosporus enabled ship passage from the Mediterranean to the Black Sea, allowing Istanbul to serve as a way station between two worlds.

As the plane descended through a layer of mist, Langdon’s eyes intently scanned the distant city, trying to catch a glimpse of the massive building they had come to search.

The site of Enrico Dandolo’s tomb.

As it turned out, Enrico Dandolo—the treacherous doge of Venice—had not been buried in Venice; rather, his remains had been interred in the heart of the stronghold he had conquered in 1202 … the sprawling city beneath them. Fittingly, Dandolo had been laid to rest in the most spectacular shrine his captured city had to offer—a building that to this day remained the crown jewel of the region.

Hagia Sophia.

Originally built in A.D. 360, Hagia Sophia had served as an Eastern Orthodox cathedral until 1204, when Enrico Dandolo and the Fourth Crusade conquered the city and turned it into a Catholic church. Later, in the fifteenth century, following the conquest of Constantinople by Fatih Sultan Mehmed, it had become a mosque, remaining an Islamic house of worship until 1935, when the building was secularized and became a museum.

A gilded mouseion of holy wisdom, Langdon thought.

Not only was Hagia Sophia adorned with more gold tile than St. Mark’s, its name—Hagia Sophia—literally meant “Holy Wisdom.”

Langdon pictured the colossal building and tried to fathom the fact that somewhere beneath it, a darkened lagoon contained a tethered, undulating sac, hovering underwater, slowly dissolving and preparing to release its contents.

Langdon prayed they were not too late.

“The building’s lower levels are flooded,” Sinskey had announced earlier in the flight, excitedly motioning for Langdon to follow her back to her work area. “You won’t believe what we just discovered. Have you ever heard of a documentary film director named Göksel Gülensoy?”

Langdon shook his head.

“While I was researching Hagia Sophia,” Sinskey explained, “I discovered that a film had been made about it. A documentary made by Gülensoy a few years back.”

“Dozens of films have been made about Hagia Sophia.”

“Yes,” she said, arriving at her work area, “but none like this.” She spun her laptop so he could see it. “Read this.”

Langdon sat down and eyed the article—a composite of various news sources including the Hürriyet Daily News—discussing Gülensoy’s newest film: In the Depths of Hagia Sophia.

As Langdon began to read, he immediately realized why Sinskey was excited. The first two words alone made Langdon glance up at her in surprise. Scuba diving?

“I know,” she said. “Just read.”

Langdon turned his eyes back to the article.

SCUBA DIVING BENEATH HAGIA SOPHIA: Documentary filmmaker Göksel Gülensoy and his exploratory scuba team have located remote flooded basins lying hundreds of feet beneath Istanbul’s heavily touristed religious structure.

In the process, they discovered numerous architectural wonders, including the 800-year-old submerged graves of martyred children, as well as submerged tunnels connecting Hagia Sophia to Topkapi Palace, Tekfur Palace, and the rumored subterranean extensions of the Anemas Dungeons.

“I believe what is beneath Hagia Sophia is much more exciting than what is above the surface,” Gülensoy explained, describing how he had been inspired to make the film after seeing an old photograph of researchers examining the foundations of Hagia Sophia by boat, paddling through a large, partially submerged hall.

“You’ve obviously found the right building!” Sinskey exclaimed. “And it sounds like there are huge pockets of navigable space beneath that building, many of them accessible without scuba gear … which may explain what we’re seeing in Zobrist’s video.”

Agent Brüder stood behind them, studying the laptop screen. “It also sounds like the waterways beneath the building spider outward to all kinds of other areas. If that Solublon bag dissolves before we arrive, there will be no way to stop the contents from spreading.”

“The contents …” Langdon ventured. “Do you have any idea what it is? I mean exactly? I know we’re dealing with a pathogen, but—”

“We’ve been analyzing the footage,” Brüder said, “which suggests that it’s indeed biological rather than chemical … that is to say, something living. Considering the small amount in the bag, we assume it’s highly contagious and has the ability to replicate. Whether it’s a waterborne contagion like a bacterium, or whether it has the potential to go airborne like a virus once it’s released, we’re not sure, but either is possible.”

Sinskey said, “We’re now gathering data on water-table temperatures in the area, trying to assess what kinds of contagious substances might thrive in those subterranean areas, but Zobrist was exceptionally talented and easily could have engineered something with unique capabilities. And I have to suspect that there was a reason Zobrist chose this location.”

Brüder gave a resigned nod and quickly relayed his assessment of the unusual dispersal mechanism—the submerged Solublon bag—the simple brilliance of which was just starting to dawn on them all. By suspending the bag underground and underwater, Zobrist had created an exceptionally stable incubation environment: one with consistent water temperature, no solar radiation, a kinetic buffer, and total privacy. By choosing a bag of the correct durability, Zobrist could leave the contagion unattended to mature for a specific duration before it self-released on schedule.

Even if Zobrist never returned to the site.

The sudden jolt of the plane touching down jarred Langdon back to his jump seat in the cockpit. The pilots braked hard and then taxied to a remote hangar, where they brought the massive plane to a stop.

Langdon half expected to be greeted by an army of WHO employees in hazmat suits. Strangely, the only party awaiting their arrival was the driver of a large white van that bore the emblem of a bright red, equal-armed cross.

The Red Cross is here? Langdon looked again, realizing it was the other entity that used the red cross. The Swiss embassy.

He unbuckled and located Sinskey as everyone prepared to deplane. “Where is everyone?” Langdon demanded. “The WHO team? The Turkish authorities? Is everyone already over at Hagia Sophia?”

Sinskey gave him an uneasy glance. “Actually,” she explained, “we have decided against alerting local authorities. We already have the ECDC’s finest SRS team with us, and it seems preferable to keep this a quiet operation for the moment, rather than creating a possible widespread panic.”

Nearby, Langdon could see Brüder and his team zipping up large black duffel bags that contained all kinds of hazmat gear—biosuits, respirators, and electronic detection equipment.

Brüder heaved his bag over his shoulder and came over. “We’re a go. We’ll enter the building, find Dandolo’s tomb, listen for water as the poem suggests, and then my team and I will reassess and decide whether to call in other authorities for support.”

Langdon already saw problems with the plan. “Hagia Sophia closes at sunset, so without local authorities, we can’t even get in.”

“We’re fine,” Sinskey said. “I have a contact in the Swiss embassy who contacted the Hagia Sophia Museum curator and asked for a private VIP tour as soon as we arrive. The curator agreed.”

Langdon almost laughed out loud. “A VIP tour for the director of the World Health Organization? And an army of soldiers carrying hazmat duffels? You don’t think that might raise a few eyebrows?”

“The SRS team and gear will stay in the car while Brüder, you, and I assess the situation,” Sinskey said. “Also, for the record, I’m not the VIP. You are.”

“I beg your pardon?!”

“We told the museum that a famous American professor had flown in with a research team to write an article on the symbols of Hagia Sofia, but their plane was delayed five hours and he missed his window to see the building. Since he and his team were leaving tomorrow morning, we were hoping—”

“Okay,” Langdon said. “I get the gist.”

“The museum is sending an employee to meet us there personally. As it turns out, he’s a big fan of your writings on Islamic art.” Sinskey gave him a tired smile, clearly trying to look optimistic. “We’ve been assured that you’ll have access to every corner of the building.”

“And more important,” Brüder declared, “we’ll have the entire place to ourselves.”

CHAPTER 85

Robert Langdon gazed blankly out the window of the van as it sped along the waterfront highway connecting Atatürk Airport to the center of Istanbul. The Swiss officials had somehow facilitated a modified customs process, and Langdon, Sinskey, and the others in the group had been en route in a matter of minutes.

Sinskey had ordered the provost and Ferris to remain aboard the C-130 with several WHO staff members and to continue trying to track the whereabouts of Sienna Brooks.

While nobody truly believed Sienna could reach Istanbul in time, there were fears she might phone one of Zobrist’s disciples in Turkey and ask for assistance in realizing Zobrist’s delusional plan before Sinskey’s team could interfere.

Would Sienna really commit mass murder? Langdon was still struggling to accept all that had happened today. It pained him to do so, but he was forced to accept the truth. You never knew her, Robert. She played you.

A light rain had begun to fall over the city, and Langdon felt suddenly weary as he listened to the repetitive swish of the windshield wipers. To his right, out on the Sea of Marmara, he could see the running lights of luxury yachts and massive tankers powering to and from the city port up ahead. All along the waterfront, illuminated minarets rose slender and elegant above their domed mosques, silent reminders that while Istanbul was a modern, secular city, its core was grounded in religion.

Langdon had always found this ten-mile strip of highway one of the prettiest drives in Europe. A perfect example of Istanbul’s clash of old and new, the road followed part of Constantine’s wall, which had been built more than sixteen centuries before the birth of the man for whom this avenue was now named—John F. Kennedy. The U.S. president had been a great admirer of Kemal Atatürk’s vision for a Turkish republic springing from the ashes of a fallen empire.

Providing unparalleled views of the sea, Kennedy Avenue wound through spectacular groves and historic parks, past the harbor in Yenikapi, and eventually threaded its way between the city limits and the Strait of Bosporus, where it continued northward all the way around the Golden Horn. There, high above the city, rose the Ottoman stronghold of Topkapi Palace. With its strategic view of the Bosporus waterway, the palace was a favorite among tourists, who visited to admire both the vistas and the staggering collection of Ottoman treasure that included the cloak and sword said to have belonged to the Prophet Muhammad himself.

We won’t be going that far, Langdon knew, picturing their destination, Hagia Sophia, which rose out of the city center not far ahead.

As they pulled off Kennedy Avenue and began snaking into the densely populated city, Langdon stared out at the crowds of people on the streets and sidewalks and felt haunted by the day’s conversations.

Overpopulation.

The plague.

Zobrist’s twisted aspirations.

Even though Langdon had understood all along exactly where this SRS mission was headed, he had not fully processed it until this moment. We are going to ground zero. He pictured the slowly dissolving bag of yellow-brown fluid and wondered how he had let himself get into this position.

The strange poem that Langdon and Sienna had unveiled on the back of Dante’s death mask had eventually guided him here, to Istanbul. Langdon had directed the SRS team to Hagia Sophia, and knew there would be more to do once they arrived.

Kneel within the gilded mouseion of holy wisdom,

and place thine ear to the ground,